A numerical study on the flow control characteristic of a cavitating venturi with one- and two-stage diffusers

A cavitating venturi in the auxiliary feed water system of a nuclear power plant is a flow control device that limits the maximum flow rate in critical conditions. In this research, a numerical study was conducted to predict the characteristics of the cavitating flow in a venturi with various geometrical configurations. Assuming axisymmetric geometry and a steady state, equations of the flow field were solved numerically. The mixture model for the multi-phase flow and the standard k-ε turbulence model were adopted. The primary diffuser angle was varied to perform detailed parametric study. The flow and pressure variations, shape of the cavitation bubble, and corresponding flow control characteristics were summarized. Finally, the calculation results were analyzed to provide a physical basis for the design limits proposed in a previous patent. It is expected that the results of this study will be useful information for the future design of an optimized venturi